Motor graders are earth-moving machines that are generally employed as a finishing tool to sculpt a surface of a construction site or roadway to a final shape and contour. Motor graders typically include a front frame and a rear frame that are joined at an articulation joint. The rear frame includes compartments for housing the power source and cooling components, the power source being operatively coupled to the rear wheels for primary propulsion of the machine, the rear wheels being arranged in tandems on opposing sides of the rear frame. The front frame includes a pair of front wheels, and supports an operator station and a blade assembly. The blade can be rotated, tilted, raised and lowered, and shifted side to side to a virtually limitless number of positions. Steering of the machine is a function of both front wheel steering and articulation of the front frame relative to the rear frame.
As should be recognized from the above, motor graders are one of the most complex types of heavy machinery to operate, including numerous hand-operated controls to steer the front wheels, position the blade, control articulation, control auxiliary devices such as rippers and plows, and various displays for monitoring machine conditions and/or functions. It requires highly skilled and focused operators to position the blade while controlling steering, particularly when performing curved path grading, cul-de-sac grading, and driving in reverse.
For example, in cul-de-sac grading, the operator is required to maneuver the motor grader around a substantially circular path while maintaining the blade at a desired distance from curbs and other obstacles. This requires that operators simultaneously control the blade, front wheel steering and articulation. Failure to properly control articulation in such instances results in the front and rear portions of the machine following separate travel paths, which can cause obstacle collisions or incomplete grading requiring multiple passes.
U.S. Pat. No. 6,152,237 to Hartman et al. discloses a method for automatically rotating a motor grader to a predetermined articulation angle. A controller obtains a present articulation angle from a displacement sensor, and, upon receiving an operator control signal, the controller is configured to articulate the motor grader from the present articulation angle to a pre-programmed articulation angle, such as a maximum right articulation angle, a maximum left articulation angle, and/or a neutral articulation angle. While this system does assist operators by providing a method of achieving a specific motor grader travel configuration with minimal operator input, during which time the operators can focus on blade control or other machine operations, it does not assist operators in maneuvering the vehicle for curved grading.
The present disclosure is directed to a steering control system and method to improve motor grader operations that addresses one or more of the problems or shortcomings set forth above.